WO2016056802A1

WO2016056802A1 - Method for reporting channel state information in wireless access system supporting unlicensed band, and apparatus for supporting same

Info

Publication number: WO2016056802A1
Application number: PCT/KR2015/010494
Authority: WO
Inventors: 김선욱; 안준기; 양석철; 서한별; 이승민; 김병훈
Original assignee: 엘지전자 주식회사
Priority date: 2014-10-06
Filing date: 2015-10-05
Publication date: 2016-04-14
Also published as: US10492092B2; US20170332267A1

Abstract

The present invention relates to a wireless access system supporting an unlicensed band, and provides a method for reporting channel state information (CSI) on the basis of a CSI measurement set, and apparatuses for supporting the method. A method, as one embodiment of the present invention, by which a terminal reports CSI in a wireless access system supporting an unlicensed band can comprise the steps of: receiving, from a base station through a primary cell (Pcell), an upper layer signal including CSI subframe set configuration information; measuring CSI on a secondary cell (Scell) in a preoccupation access period (PAP) or a non-preoccupation access period (non-PAP) on the basis of the CSI subframe set configuration information; and transmitting a CSI report including the measured CSI to the base station. At this time, the non-PAP is set as a first CSI subframe set, the PAP is set as a second CSI subframe set, the first CSI subframe set and the second CSI subframe set are set in the terminal through the CSI subframe set configuration information, and the Scell can be configured in an unlicensed band.

Description

Method of reporting channel status information in wireless access system supporting unlicensed band and apparatus supporting same

The present invention relates to a wireless access system that supports an unlicensed band, and more particularly, to a method for reporting CSI based on a channel status information (CSI) measurement set and an apparatus for supporting the same.

Wireless access systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless access system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency (SC-FDMA). division multiple access) system.

The present invention relates to a wireless access system supporting an unlicensed band, and more particularly, to a method for reporting channel state information and devices for supporting the same.

An object of the present invention is to provide a method for efficiently transmitting and receiving data in a wireless access system supporting an unlicensed band and a licensed band.

Another object of the present invention is to divide a unlicensed band into a time-based access period (PAP) and a non-shared-time period (Non-PAP), and to establish a subframe measurement set in PAP and / or Non-PAP. To provide.

Another object of the present invention is to provide a method for performing periodic or aperiodic CSI reporting within a limited CSI measurement set when setting a limited CSI measurement set.

It is still another object of the present invention to provide a method for performing periodic or aperiodic CSI reporting when no limited CSI measurement set is set.

Still another object of the present invention is to provide a method for sharing configuration information on PAP and non-PAP between a base station or a cell.

It is yet another object of the present invention to provide devices which support these methods.

Technical objects to be achieved in the present invention are not limited to the above-mentioned matters, and other technical problems which are not mentioned are those skilled in the art from the embodiments of the present invention to be described below. Can be considered.

The present invention relates to a wireless access system supporting an unlicensed band, and provides a method for reporting CSI based on a channel state information (CSI) measurement set and apparatuses for supporting the same.

In one aspect of the present invention, a method for a UE to report channel state information (CSI) in a wireless access system supporting an unlicensed band includes: transmitting a higher layer signal including CSI subframe set configuration information through a primary cell (P cell); Measuring and measuring the CSI for the secondary cell (S cell) in the PAS or non-PAP based on the step of receiving from the base station and the CSI subframe set configuration information And transmitting the CSI report including the CSI to the base station managing the Pcell and / or the Scell. In this case, the non-PAP is set to the first CSI subframe set, the PAP is set to the second CSI subframe set, the terminal is set through the CSI subframe set configuration information, the first CSI subframe set and the second CSI subframe After the set is established, the SCell may be configured in the unlicensed band.

In another aspect of the present invention, a terminal for reporting channel state information (CSI) in a wireless access system supporting an unlicensed band may include a transmitter, a receiver, and a processor operatively connected to the transmitter and the receiver to report the CSI. Can be. At this time, the processor receives the upper layer signal including the CSI subframe set configuration information from the primary cell (P cell) by controlling the receiver; Measuring the CSI for the secondary cell (S cell) in the shared base access section (PAP) or the non-shared base access section (non-PAP) based on the CSI subframe set configuration information; And transmit the CSI report including the measured CSI to a base station managing the Pcell and / or the Scell by controlling the transmitter, wherein the non-PAP is set to the first CSI subframe set, and the PAP is the second CSI subframe. The UE is configured with a frame set, the UE receives the first CSI subframe set and the second CSI subframe set through the CSI subframe set configuration information, and the SCell may be configured in the unlicensed band.

The PAP may be set as a section in which data is transmitted and received regardless of whether or not the S cell is idle, and the non-PAP may be set as a section in which data is transmitted and received only in a transmission opportunity section (TxOP) in which the S cell is idle.

If the CSI report is a periodic CSI report transmitted periodically, the UE may be configured to measure only the CSI for the second CSI subframe set and transmit the CSI report to the base station.

Or, if the CSI report is periodically transmitted CSI report, the UE can transmit the CSI report to the base station by measuring the CSI in the TxOP in the first CSI subframe set.

If the CSI report is an aperiodic CSI report requested by the base station, the UE may receive a physical downlink control channel including an aperiodic CSI request field from the Pcell, and the aperiodic CSI request field is the first CSI subfield. It may be configured to request CSI reporting for the frame set or the second CSI subframe set.

The terminal may be configured to perform interferometry for the neighbor cell only in the second subframe set.

The terminal may receive downlink data from the SCell. In this case, a power adjustment parameter used when transmitting downlink data may be set differently for each of a first subframe set and a second subframe set.

The above-described aspects of the present invention are merely some of the preferred embodiments of the present invention, and various embodiments reflecting the technical features of the present invention will be described in detail by those skilled in the art. Based on the description, it can be derived and understood.

According to embodiments of the present invention has the following effects.

First, data can be efficiently transmitted and received in a wireless access system supporting an unlicensed band and a licensed band.

Second, dividing the unlicensed band into time-sharing periods (PAP) and non-sharing periods (Non-PAP) on the time base, and efficiently operating the unlicensed band by setting subframe measurement sets in PAP and / or Non-PAP. can do.

Third, in case of setting the limited CSI measurement set, the UE may perform appropriate periodic or aperiodic CSI reporting according to the characteristics of the unlicensed band within the limited CSI measurement set.

Fourth, by sharing configuration information for PAP and non-PAP between base stations or cells, inter-cell or inter-base station interference can be minimized.

Effects obtained in the embodiments of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above are usually described in the technical field to which the present invention pertains from the description of the embodiments of the present invention. Can be clearly derived and understood by those who have That is, unintended effects of practicing the present invention may also be derived from those skilled in the art from the embodiments of the present invention.

It is included as part of the detailed description to assist in understanding the present invention, and the accompanying drawings provide various embodiments of the present invention. In addition, the accompanying drawings are used to describe embodiments of the present invention in conjunction with the detailed description.

1 is a diagram illustrating a physical channel and a signal transmission method using the same.

2 is a diagram illustrating an example of a structure of a radio frame.

3 is a diagram illustrating a resource grid for a downlink slot.

4 is a diagram illustrating an example of a structure of an uplink subframe.

5 is a diagram illustrating an example of a structure of a downlink subframe.

6 is a diagram illustrating an example of carrier aggregation used in a component carrier (CC) and LTE_A system.

7 shows a subframe structure of an LTE-A system according to cross carrier scheduling.

8 is a diagram illustrating an example of a configuration of a serving cell according to cross carrier scheduling.

9 is a diagram illustrating one of the SRS transmission methods used in embodiments of the present invention.

FIG. 10 is a diagram illustrating an example of a subframe to which a cell specific reference signal (CRS) is allocated, which can be used in embodiments of the present invention.

FIG. 11 is a diagram illustrating an example in which legacy PDCCH, PDSCH, and E-PDCCH used in an LTE / LTE-A system are multiplexed.

12 is a diagram illustrating an example of a CA environment supported by an LTE-U system.

FIG. 13 is a diagram illustrating one method of setting a TxOP interval. FIG.

14 is a diagram illustrating one method of setting a TxOP interval.

FIG. 15 is a diagram for explaining one of methods for performing periodic CSI reporting on a subframe set configured in an unlicensed band.

FIG. 16 is a diagram for describing one of methods for performing aperiodic CSI reporting on a subframe set configured in an unlicensed band.

The apparatus described in FIG. 17 is a means in which the methods described in FIGS. 1 to 16 may be implemented.

The present invention relates to a wireless access system supporting an unlicensed band, and proposes a method for reporting CSI based on a channel state information (CSI) measurement set, and apparatuses for supporting the same.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps which may obscure the gist of the present invention are not described, and procedures or steps that can be understood by those skilled in the art are not described.

Throughout the specification, when a part is said to "comprising" (or including) a component, this means that it may further include other components, except to exclude other components unless specifically stated otherwise. do. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have. Also, "a or an", "one", "the", and the like are used differently in the context of describing the present invention (particularly in the context of the following claims). Unless otherwise indicated or clearly contradicted by context, it may be used in the sense including both the singular and the plural.

In the present specification, embodiments of the present invention have been described based on data transmission / reception relations between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, various operations performed for communication with a mobile station in a network consisting of a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an advanced base station (ABS), or an access point.

Further, in embodiments of the present invention, a terminal may be a user equipment (UE), a mobile station (MS), a subscriber station (SS), or a mobile subscriber station (MSS). It may be replaced with terms such as a mobile terminal or an advanced mobile station (AMS).

Also, the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service, and the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in uplink, a mobile station may be a transmitting end and a base station may be a receiving end. Similarly, in downlink, a mobile station may be a receiving end and a base station may be a transmitting end.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the IEEE 802.xx system, the 3rd Generation Partnership Project (3GPP) system, the 3GPP LTE system, and the 3GPP2 system, which are wireless access systems, and in particular, the present invention. Embodiments of the may be supported by 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321 and 3GPP TS 36.331 documents. That is, obvious steps or portions not described among the embodiments of the present invention may be described with reference to the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the invention may be practiced.

In addition, specific terms used in the embodiments of the present invention are provided to help the understanding of the present invention, and the use of the specific terms may be changed into other forms without departing from the technical spirit of the present invention. .

For example, the term Transmission Opportunity Period (TxOP) may be used in the same meaning as the term transmission period or RRP (Reserved Resource Period). Also, the List Before Talk (LBT) process may be performed for the same purpose as the carrier sensing process for determining whether the channel state is idle.

Hereinafter, a 3GPP LTE / LTE-A system will be described as an example of a wireless access system in which embodiments of the present invention can be used.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be applied to various radio access systems.

CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA).

UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. The LTE-A (Advanced) system is an improved system of the 3GPP LTE system. In order to clarify the description of the technical features of the present invention, embodiments of the present invention will be described based on the 3GPP LTE / LTE-A system, but can also be applied to IEEE 802.16e / m system and the like.

1. 3GPP LTE/LTE_A 시스템1.3GPP LTE / LTE_A System

In a wireless access system, a terminal receives information from a base station through downlink (DL) and transmits information to the base station through uplink (UL). The information transmitted and received by the base station and the terminal includes general data information and various control information, and various physical channels exist according to the type / use of the information they transmit and receive.

1.1 시스템 일반1.1 System General

1 is a diagram for explaining physical channels that can be used in embodiments of the present invention and a signal transmission method using the same.

When the power is turned off again or a new cell enters the cell, the initial cell search operation such as synchronizing with the base station is performed in step S11. To this end, the UE receives a Primary Synchronization Channel (P-SCH) and a Secondary Synchronization Channel (S-SCH) from the base station, synchronizes with the base station, and obtains information such as a cell ID.

Thereafter, the terminal may receive a physical broadcast channel (PBCH) signal from the base station to obtain broadcast information in a cell.

On the other hand, the terminal may receive a downlink reference signal (DL RS) in the initial cell search step to confirm the downlink channel state.

After completing the initial cell search, the UE receives a physical downlink control channel (PDCCH) and a physical downlink control channel (PDSCH) according to the physical downlink control channel information in step S12. Specific system information can be obtained.

Subsequently, the terminal may perform a random access procedure as in steps S13 to S16 to complete the access to the base station. To this end, the UE transmits a preamble through a physical random access channel (PRACH) (S13), a response message to the preamble through a physical downlink control channel and a corresponding physical downlink shared channel. Can be received (S14). In case of contention-based random access, the UE may perform contention resolution such as transmitting an additional physical random access channel signal (S15) and receiving a physical downlink control channel signal and a corresponding physical downlink shared channel signal (S16). Procedure).

After performing the above-described procedure, the UE subsequently receives a physical downlink control channel signal and / or a physical downlink shared channel signal (S17) and a physical uplink shared channel (PUSCH) as a general uplink / downlink signal transmission procedure. A transmission (Uplink Shared Channel) signal and / or a Physical Uplink Control Channel (PUCCH) signal may be transmitted (S18).

The control information transmitted from the terminal to the base station is collectively referred to as uplink control information (UCI). UCI includes Hybrid Automatic Repeat and reQuest Acknowledgement / Negative-ACK (HARQ-ACK / NACK), Scheduling Request (SR), Channel Quality Indication (CQI), Precoding Matrix Indication (PMI), and Rank Indication (RI). .

In the LTE system, UCI is generally transmitted periodically through the PUCCH, but may be transmitted through the PUSCH when control information and traffic data should be transmitted at the same time. In addition, the UCI may be aperiodically transmitted through the PUSCH by the request / instruction of the network.

2 shows a structure of a radio frame used in embodiments of the present invention.

2 (a) shows a frame structure type 1. The type 1 frame structure can be applied to both full duplex Frequency Division Duplex (FDD) systems and half duplex FDD systems.

One radio frame has a length of Tf = 307 200 * Ts = 10 ms, an equal length of Tslot = 15360 * Ts = 0.5 ms, and consists of 20 slots indexed from 0 to 19. One subframe is defined as two consecutive slots, and the i-th subframe includes slots corresponding to 2i and 2i + 1. That is, a radio frame consists of 10 subframes. The time taken to transmit one subframe is called a transmission time interval (TTI). Here, Ts represents a sampling time and is represented by T _s = 1 / (15 kHz x 2048) = 3.2552 x 10 ^-8 (about 33 ns). The slot includes a plurality of OFDM symbols or SC-FDMA symbols in the time domain and a plurality of resource blocks in the frequency domain.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain. Since 3GPP LTE uses OFDMA in downlink, the OFDM symbol is for representing one symbol period. The OFDM symbol may be referred to as one SC-FDMA symbol or symbol period. A resource block is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot.

In a full-duplex FDD system, 10 subframes may be used simultaneously for downlink transmission and uplink transmission during each 10ms period. At this time, uplink and downlink transmission are separated in the frequency domain. On the other hand, in the case of a half-duplex FDD system, the terminal cannot simultaneously transmit and receive.

The structure of the radio frame described above is just one example, and the number of subframes included in the radio frame, the number of slots included in the subframe, and the number of OFDM symbols included in the slot may be variously changed.

2 (b) shows a frame structure type 2. Type 2 frame structure is applied to the TDD system. One radio frame has a length of Tf = 307200 * Ts = 10ms and consists of two half-frames having a length of 153600 * Ts = 5ms. Each half frame consists of five subframes having a length of 30720 * Ts = 1ms. The i-th subframe consists of two slots each having a length of Tslot = 15360 * Ts = 0.5ms corresponding to 2i and 2i + 1. Here, Ts represents a sampling time and is represented by T _s = 1 / (15 kHz x 2048) = 3.2552 x 10 ^-8 (about 33 ns).

The type 2 frame includes a special subframe consisting of three fields: a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). Here, the DwPTS is used for initial cell search, synchronization or channel estimation in the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. The guard period is a period for removing interference generated in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

Table 1 below shows the structure of the special frame (length of DwPTS / GP / UpPTS).

Table 1

3 is a diagram illustrating a resource grid for a downlink slot that can be used in embodiments of the present invention.

Referring to FIG. 3, one downlink slot includes a plurality of OFDM symbols in the time domain. Here, one downlink slot includes seven OFDM symbols, and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto.

Each element on the resource grid is a resource element, and one resource block includes 12 × 7 resource elements. The number NDL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth. The structure of the uplink slot may be the same as the structure of the downlink slot.

4 shows a structure of an uplink subframe that can be used in embodiments of the present invention.

Referring to FIG. 4, an uplink subframe may be divided into a control region and a data region in the frequency domain. The control region is allocated a PUCCH carrying uplink control information. In the data area, a PUSCH carrying user data is allocated. In order to maintain a single carrier characteristic, one UE does not simultaneously transmit a PUCCH and a PUSCH. The PUCCH for one UE is allocated an RB pair in a subframe. RBs belonging to the RB pair occupy different subcarriers in each of the two slots. The RB pair assigned to this PUCCH is said to be frequency hopping at the slot boundary.

5 shows a structure of a downlink subframe that can be used in embodiments of the present invention.

Referring to FIG. 5, up to three OFDM symbols from the OFDM symbol index 0 in the first slot in the subframe are control regions to which control channels are allocated, and the remaining OFDM symbols are data regions to which the PDSCH is allocated. to be. One example of a downlink control channel used in 3GPP LTE includes a Physical Control Format Indicator Channel (PCFICH), a PDCCH, and a Physical Hybrid-ARQ Indicator Channel (PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols (ie, the size of the control region) used for transmission of control channels within the subframe. The PHICH is a response channel for the uplink and carries an ACK (Acknowledgement) / NACK (Negative-Acknowledgement) signal for a hybrid automatic repeat request (HARQ). Control information transmitted through the PDCCH is called downlink control information (DCI). The downlink control information includes uplink resource allocation information, downlink resource allocation information or an uplink transmission (Tx) power control command for a certain terminal group.

1.2 PDCCH(Physical Downlink Control Channel)1.2 Physical Downlink Control Channel (PDCCH)

1.2.1 PDCCH 일반1.2.1 PDCCH General

The PDCCH includes resource allocation and transmission format (ie, DL-Grant) of downlink shared channel (DL-SCH) and resource allocation information (ie, uplink grant (UL-) of uplink shared channel (UL-SCH). Grant)), paging information on a paging channel (PCH), system information on a DL-SCH, and an upper-layer control message such as a random access response transmitted on a PDSCH. It may carry resource allocation, a set of transmission power control commands for individual terminals in a certain terminal group, information on whether Voice over IP (VoIP) is activated or the like.

A plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs. The PDCCH consists of an aggregation of one or several consecutive control channel elements (CCEs). The PDCCH composed of one or several consecutive CCEs may be transmitted through the control region after subblock interleaving. CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to a state of a radio channel. The CCE corresponds to a plurality of resource element groups (REGs). The format of the PDCCH and the number of bits of the PDCCH are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.

1.2.2 PDCCH 구조1.2.2 PDCCH Structure

A plurality of multiplexed PDCCHs for a plurality of terminals may be transmitted in a control region. The PDCCH is composed of one or more consecutive CCE aggregations (CCE aggregation). CCE refers to a unit corresponding to nine sets of REGs consisting of four resource elements. Four Quadrature Phase Shift Keying (QPSK) symbols are mapped to each REG. Resource elements occupied by a reference signal (RS) are not included in the REG. That is, the total number of REGs in the OFDM symbol may vary depending on whether a cell specific reference signal exists. The concept of REG, which maps four resource elements to one group, can also be applied to other downlink control channels (eg, PCFICH or PHICH). If REG not assigned to PCFICH or PHICH is N _REG , the number of CCEs available in the system is N _CCE = floor (N _REG / 9), and each CCE has an index from 0 to N _CCE -1.

In order to simplify the decoding process of the UE, the PDCCH format including n CCEs may start with a CCE having an index equal to a multiple of n. That is, when the CCE index is i, it may start from a CCE satisfying imod (n) = 0.

The base station may use {1, 2, 4, 8} CCEs to configure one PDCCH signal, wherein {1, 2, 4, 8} is called a CCE aggregation level. The number of CCEs used for transmission of a specific PDCCH is determined by the base station according to the channel state. For example, one CCE may be sufficient for a PDCCH for a terminal having a good downlink channel state (close to the base station). On the other hand, in case of a UE having a bad channel state (when it is at a cell boundary), eight CCEs may be required for sufficient robustness. In addition, the power level of the PDCCH may also be adjusted to match the channel state.

Table 2 below shows a PDCCH format, and four PDCCH formats are supported as shown in Table 2 according to the CCE aggregation level.

TABLE 2

PDCCH Format	CCE Count (n)	REG Count	PDCCH Bit Count
0	One	9	72
One	2	18	144
2	4	36	288
3	8	72	576

The reason why the CCE aggregation level is different for each UE is because a format or a modulation and coding scheme (MCS) level of control information carried on the PDCCH is different. The MCS level refers to a code rate and a modulation order used for data coding. Adaptive MCS levels are used for link adaptation. In general, three to four MCS levels may be considered in a control channel for transmitting control information.

Referring to the format of the control information, control information transmitted through the PDCCH is referred to as downlink control information (DCI). According to the DCI format, the configuration of information carried in the PDCCH payload may vary. The PDCCH payload means an information bit. Table 3 below shows DCI according to DCI format.

TABLE 3

DCI format	Contents
Format
0	Resource grants for PUSCH transmissions (uplink)
Format 1	Resource assignments for single codeword PDSCH transmission ( transmission modes 1, 2 and 7)
Format 1A	Compact signaling of resource assignments for sigle codeword PDSCH (all modes)
Format 1B	Compact resource assignments for PDSCH using rank-1 closed loop precoding (mode 6)
Format 1C	Very compact resource assignments for PDSCH (eg, paging / broadcast system information)
Format 1D	Compact resource assignments for PDSCH using multi-user MIMO (mode 5)
Format 2	Resource assignments for PDSCH for closed loop MIMO operation (mode 4)
Format 2A	resource assignments for PDSCH for open loop MIMO operation (mode 3)
Format 3 / 3A	Power control commands for PUCCH and PUSCH with 2-bit / 1-bit power adjustment
Format
4	Scheduling of PUSCH in one UL cell with multi-antenna port transmission mode

Referring to Table 3, a DCI format includes a format 0 for PUSCH scheduling, a format 1 for scheduling one PDSCH codeword, a format 1A for compact scheduling of one PDSCH codeword, and a very much DL-SCH. Format 1C for simple scheduling, format 2 for PDSCH scheduling in closed-loop spatial multiplexing mode, format 2A for PDSCH scheduling in open-loop spatial multiplexing mode, for uplink channel There are formats 3 and 3A for the transmission of Transmission Power Control (TPC) commands. DCI format 1A may be used for PDSCH scheduling, regardless of which transmission mode is configured for the UE.

The PDCCH payload length may vary depending on the DCI format. In addition, the type and length thereof of the PDCCH payload may vary depending on whether it is a simple scheduling or a transmission mode set in the terminal.

The transmission mode may be configured for the UE to receive downlink data through the PDSCH. For example, the downlink data through the PDSCH may include scheduled data, paging, random access response, or broadcast information through BCCH. Downlink data through the PDSCH is related to the DCI format signaled through the PDCCH. The transmission mode may be set semi-statically to the terminal through higher layer signaling (eg, RRC (Radio Resource Control) signaling). The transmission mode may be classified into single antenna transmission or multi-antenna transmission.

The terminal is set to a semi-static transmission mode through higher layer signaling. For example, multi-antenna transmission includes transmit diversity, open-loop or closed-loop spatial multiplexing, and multi-user-multiple input multiple outputs. ) Or beamforming. Transmit diversity is a technique of increasing transmission reliability by transmitting the same data in multiple transmit antennas. Spatial multiplexing is a technology that allows high-speed data transmission without increasing the bandwidth of the system by simultaneously transmitting different data from multiple transmit antennas. Beamforming is a technique of increasing the signal to interference plus noise ratio (SINR) of a signal by applying weights according to channel conditions in multiple antennas.

The DCI format is dependent on a transmission mode configured in the terminal (depend on). The UE has a reference DCI format that monitors according to a transmission mode configured for the UE. The transmission mode set in the terminal may have ten transmission modes as follows.

(1) transmission mode 1: single antenna port; Port 0

(2) Transmission Mode 2: Transmit Diversity

(3) Transmission Mode 3: Open-loop Spatial Multiplexing

(4) Transmission Mode 4: Closed-loop Spatial Multiplexing

(5) Transmission Mode 5: Multi-User MIMO

(6) Transmission mode 6: closed loop, rank = 1 precoding

(7) Transmission mode 7: Precoding supporting single layer transmission not based on codebook

(8) Transmission mode 8: Precoding supporting up to two layers not based on codebook

(9) Transmission mode 9: Precoding supporting up to eight layers not based on codebook

(10) Transmission mode 10: precoding supporting up to eight layers, used for CoMP, not based on codebook

1.2.3 PDCCH 전송1.2.3 PDCCH Transmission

The base station determines the PDCCH format according to the DCI to be transmitted to the terminal, and attaches a CRC (Cyclic Redundancy Check) to the control information. In the CRC, a unique identifier (for example, a Radio Network Temporary Identifier (RNTI)) is masked according to an owner or a purpose of the PDCCH. If it is a PDCCH for a specific terminal, a unique identifier (eg, C-RNTI (Cell-RNTI)) of the terminal may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier (eg, P-RNTI (P-RNTI)) may be masked to the CRC. If the system information, more specifically, the PDCCH for the System Information Block (SIB), a system information identifier (eg, a System Information RNTI (SI-RNTI)) may be masked to the CRC. A random access-RNTI (RA-RNTI) may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the UE.

Subsequently, the base station performs channel coding on the control information added with the CRC to generate coded data. In this case, channel coding may be performed at a code rate according to the MCS level. The base station performs rate matching according to the CCE aggregation level allocated to the PDCCH format, modulates the coded data, and generates modulation symbols. At this time, a modulation sequence according to the MCS level can be used. The modulation symbols constituting one PDCCH may have one of 1, 2, 4, and 8 CCE aggregation levels. Thereafter, the base station maps modulation symbols to physical resource elements (CCE to RE mapping).

1.2.4 블라인드 디코딩(BS: Blind Decoding)1.2.4 Blind Decoding (BS)

A plurality of PDCCHs may be transmitted in one subframe. That is, the control region of one subframe includes a plurality of CCEs having indices 0 to N _{CCE, k} −1. Here, N _{CCE, k} means the total number of CCEs in the control region of the kth subframe. The UE monitors the plurality of PDCCHs in every subframe. Here, monitoring means that the UE attempts to decode each of the PDCCHs according to the monitored PDCCH format.

In the control region allocated in the subframe, the base station does not provide information on where the PDCCH corresponding to the UE is. In order to receive the control channel transmitted from the base station, the UE cannot know where the PDCCH is transmitted in which CCE aggregation level or DCI format. Therefore, the UE monitors the aggregation of PDCCH candidates in a subframe. Find the PDCCH. This is called blind decoding (BD). Blind decoding refers to a method in which a UE de-masks its UE ID in a CRC portion and then checks the CRC error to determine whether the corresponding PDCCH is its control channel.

In the active mode, the UE monitors the PDCCH of every subframe in order to receive data transmitted to the UE. In the DRX mode, the UE wakes up in the monitoring interval of every DRX cycle and monitors the PDCCH in a subframe corresponding to the monitoring interval. A subframe in which PDCCH monitoring is performed is called a non-DRX subframe.

In order to receive the PDCCH transmitted to the UE, the UE must perform blind decoding on all CCEs present in the control region of the non-DRX subframe. Since the UE does not know which PDCCH format is transmitted, it is necessary to decode all PDCCHs at the CCE aggregation level possible until blind decoding of the PDCCH is successful in every non-DRX subframe. Since the UE does not know how many CCEs the PDCCH uses for itself, the UE should attempt detection at all possible CCE aggregation levels until the blind decoding of the PDCCH succeeds.

In the LTE system, a search space (SS) concept is defined for blind decoding of a terminal. The search space means a PDCCH candidate set for the UE to monitor and may have a different size according to each PDCCH format. The search space may include a common search space (CSS) and a UE-specific / dedicated search space (USS).

In the case of the common search space, all terminals can know the size of the common search space, but the terminal specific search space can be set individually for each terminal. Accordingly, the UE must monitor both the UE-specific search space and the common search space in order to decode the PDCCH, thus performing a maximum of 44 blind decoding (BDs) in one subframe. This does not include blind decoding performed according to different CRC values (eg, C-RNTI, P-RNTI, SI-RNTI, RA-RNTI).

Due to the limitation of the search space, the base station may not be able to secure the CCE resources for transmitting the PDCCH to all the terminals to transmit the PDCCH in a given subframe. This is because resources remaining after the CCE location is allocated may not be included in the search space of a specific UE. A terminal specific hopping sequence may be applied to the starting point of the terminal specific search space to minimize this barrier that may continue to the next subframe.

Table 4 shows the sizes of the common search space and the terminal specific search space.

Table 4

PDCCH Format	CCE Count (n)	Candidate count in CSS	Candidate Count in USS
0	One	-	6
One	2	-	6
2	4	4	2
3	8	2	2

In order to reduce the load of the UE according to the number of blind decoding attempts, the UE does not simultaneously perform searches according to all defined DCI formats. Specifically, the terminal always performs a search for DCI formats 0 and 1A in the terminal specific search space (USS). In this case, the DCI formats 0 and 1A have the same size, but the UE may distinguish the DCI formats by using a flag used for distinguishing the DCI formats 0 and 1A included in the PDCCH. In addition, a DCI format other than DCI format 0 and DCI format 1A may be required for the UE. Examples of the DCI formats include 1, 1B, and 2.

In the common search space (CSS), the UE may search for DCI formats 1A and 1C. In addition, the UE may be configured to search for DCI format 3 or 3A, and DCI formats 3 and 3A have the same size as DCI formats 0 and 1A, but the UE uses a CRC scrambled by an identifier other than the UE specific identifier. The DCI format can be distinguished.

Search space

Set level

PDCCH candidate set according to the. The CCE according to the PDCCH candidate set m of the search space may be determined by Equation 1 below.

Equation 1

Here, M ^(L) represents the number of PDCCH candidates according to CCE aggregation level L for monitoring in search space,

to be. i is an index designating an individual CCE in each PDCCH candidate in the PDCCH, and i = 0, ..., L-1.

N _s represents a slot index in a radio frame.

As described above, the UE monitors both the UE-specific search space and the common search space to decode the PDCCH. Here, the common search space (CSS) supports PDCCHs having an aggregation level of {4, 8}, and the UE specific search space (USS) supports PDCCHs having an aggregation level of {1, 2, 4, 8}. . Table 5 shows PDCCH candidates monitored by the UE.

Table 5

Referring to Equation 1, Y _k is set to 0 for two aggregation levels, L = 4 and L = 8 for a common search space. On the other hand, for the UE-specific search space for the aggregation level L, Y _k is defined as in Equation 2.

Equation 2

here,

And n _RNTI represents an RNTI value. Further, A = 39827 and D = 65537.

2. 캐리어 병합(CA: Carrier Aggregation) 환경 2. Carrier Aggregation (CA) Environment

2.1 CA 일반2.1 CA General

3GPP LTE (3rd Generation Partnership Project Long Term Evolution (Rel-8 or Rel-9) system (hereinafter referred to as LTE system) is a multi-carrier modulation (MCM) that divides a single component carrier (CC) into multiple bands. Multi-Carrier Modulation) is used. However, in the 3GPP LTE-Advanced system (hereinafter, LTE-A system), a method such as Carrier Aggregation (CA) may be used in which one or more component carriers are combined to support a wider system bandwidth than the LTE system. have. Carrier aggregation may be replaced with the words carrier aggregation, carrier matching, multi-component carrier environment (Multi-CC) or multicarrier environment.

In the present invention, the multi-carrier means the aggregation of carriers (or carrier aggregation), wherein the aggregation of carriers means not only merging between contiguous carriers but also merging between non-contiguous carriers. In addition, the number of component carriers aggregated between downlink and uplink may be set differently. The case where the number of downlink component carriers (hereinafter referred to as 'DL CC') and the number of uplink component carriers (hereinafter referred to as 'UL CC') is the same is called symmetric merging. This is called asymmetric merging. Such carrier aggregation may be used interchangeably with terms such as carrier aggregation, bandwidth aggregation, spectrum aggregation, and the like.

Carrier aggregation, in which two or more component carriers are combined, aims to support up to 100 MHz bandwidth in an LTE-A system. When combining one or more carriers having a bandwidth smaller than the target band, the bandwidth of the combining carrier may be limited to the bandwidth used by the existing system to maintain backward compatibility with the existing IMT system.

For example, the existing 3GPP LTE system supports {1.4, 3, 5, 10, 15, 20} MHz bandwidth, and the 3GPP LTE-advanced system (i.e., LTE-A) supports the above for compatibility with the existing system. Only bandwidths can be used to support bandwidths greater than 20 MHz. In addition, the carrier aggregation system used in the present invention may support carrier aggregation by defining a new bandwidth regardless of the bandwidth used in the existing system.

In addition, the carrier aggregation may be divided into an intra-band CA and an inter-band CA. Intra-band carrier merging means that a plurality of DL CCs and / or UL CCs are located adjacent to or in proximity to frequency. In other words, it may mean that the carrier frequencies of the DL CCs and / or UL CCs are located in the same band. On the other hand, an environment far from the frequency domain may be referred to as an inter-band CA. In other words, it may mean that the carrier frequencies of the plurality of DL CCs and / or UL CCs are located in different bands. In this case, the terminal may use a plurality of radio frequency (RF) terminals to perform communication in a carrier aggregation environment.

The LTE-A system uses the concept of a cell to manage radio resources. The carrier aggregation environment described above may be referred to as a multiple cell environment. A cell is defined as a combination of a downlink resource (DL CC) and an uplink resource (UL CC), but the uplink resource is not an essential element. Accordingly, the cell may be configured with only downlink resources or with downlink resources and uplink resources.

For example, when a specific UE has only one configured serving cell, it may have one DL CC and one UL CC. However, when a specific terminal has two or more configured serving cells, it may have as many DL CCs as the number of cells and the number of UL CCs may be the same or smaller than that. Alternatively, the DL CC and the UL CC may be configured on the contrary. That is, when a specific UE has a plurality of configured serving cells, a carrier aggregation environment in which a UL CC has more than the number of DL CCs may be supported.

Carrier coupling (CA) may also be understood as the merging of two or more cells, each having a different carrier frequency (center frequency of the cell). The term 'cell' in terms of carrier combining is described in terms of frequency, and should be distinguished from 'cell' as a geographical area covered by a commonly used base station. Hereinafter, the above-described intra-band carrier merging is referred to as an intra-band multi-cell, and inter-band carrier merging is referred to as an inter-band multi-cell.

The cell used in the LTE-A system includes a primary cell (P cell) and a secondary cell (S cell). The PCell and the SCell may be used as serving cells. In case of the UE that is in the RRC_CONNECTED state but the carrier aggregation is not configured or does not support the carrier aggregation, there is only one serving cell composed of the PCell. On the other hand, in case of a UE in RRC_CONNECTED state and carrier aggregation is configured, one or more serving cells may exist, and the entire serving cell includes a PCell and one or more SCells.

Serving cells (P cell and S cell) may be configured through an RRC parameter. PhyS cell Id is a cell's physical layer identifier and has an integer value from 0 to 503. SCell Index is a short identifier used to identify SCell and has an integer value from 1 to 7. ServCellIndex is a short identifier used to identify a serving cell (P cell or S cell) and has an integer value from 0 to 7. A value of 0 is applied to the P cell, and the S cell Index is given in advance to apply to the S cell. That is, a cell having the smallest cell ID (or cell index) in ServCellIndex becomes a P cell.

P cell refers to a cell operating on a primary frequency (or primary CC). The UE may be used to perform an initial connection establishment process or to perform a connection re-establishment process, and may also refer to a cell indicated in a handover process. In addition, the P cell refers to a cell serving as a center of control-related communication among serving cells configured in a carrier aggregation environment. That is, the terminal may receive and transmit a PUCCH only in its own Pcell, and may use only the Pcell to acquire system information or change a monitoring procedure. E-UTRAN (Evolved Universal Terrestrial Radio Access) changes only the Pcell for the handover procedure by using an RRC ConnectionReconfigutaion message of a higher layer including mobility control information to a UE supporting a carrier aggregation environment. It may be.

The S cell may refer to a cell operating on a secondary frequency (or, secondary CC). Only one PCell may be allocated to a specific UE, and one or more SCells may be allocated. The SCell is configurable after the RRC connection is established and may be used to provide additional radio resources. PUCCH does not exist in the remaining cells excluding the P cell, that is, the S cell, among the serving cells configured in the carrier aggregation environment.

When the E-UTRAN adds the SCell to the UE supporting the carrier aggregation environment, the E-UTRAN may provide all system information related to the operation of the related cell in the RRC_CONNECTED state through a dedicated signal. The change of the system information may be controlled by the release and addition of the related SCell, and at this time, an RRC connection reconfigutaion message of a higher layer may be used. The E-UTRAN may transmit specific signaling having different parameters for each terminal, rather than broadcasting in the related SCell.

After the initial security activation process begins, the E-UTRAN may configure a network including one or more Scells in addition to the Pcells initially configured in the connection establishment process. In the carrier aggregation environment, the Pcell and the SCell may operate as respective component carriers. In the following embodiments, the primary component carrier (PCC) may be used in the same sense as the PCell, and the secondary component carrier (SCC) may be used in the same sense as the SCell.

FIG. 6 is a diagram illustrating an example of carrier aggregation used in a component carrier (CC) and an LTE_A system used in embodiments of the present invention.

6 (a) shows a single carrier structure used in an LTE system. Component carriers include a DL CC and an UL CC. One component carrier may have a frequency range of 20 MHz.

6 (b) shows a carrier aggregation structure used in the LTE_A system. 6 (b) shows a case where three component carriers having a frequency size of 20 MHz are combined. Although there are three DL CCs and three UL CCs, the number of DL CCs and UL CCs is not limited. In case of carrier aggregation, the UE may simultaneously monitor three CCs, receive downlink signals / data, and transmit uplink signals / data.

If N DL CCs are managed in a specific cell, the network may allocate M (M ≦ N) DL CCs to the UE. In this case, the UE may monitor only M limited DL CCs and receive a DL signal. In addition, the network may assign L (L ≦ M ≦ N) DL CCs to allocate a main DL CC to the UE, in which case the UE must monitor the L DL CCs. This method can be equally applied to uplink transmission.

The linkage between the carrier frequency (or DL CC) of the downlink resource and the carrier frequency (or UL CC) of the uplink resource may be indicated by a higher layer message or system information such as an RRC message. For example, a combination of DL resources and UL resources may be configured by a linkage defined by SIB2 (System Information Block Type2). Specifically, the linkage may mean a mapping relationship between a DL CC on which a PDCCH carrying a UL grant is transmitted and a UL CC using the UL grant, and a DL CC (or UL CC) and HARQ ACK on which data for HARQ is transmitted. It may mean a mapping relationship between UL CCs (or DL CCs) through which a / NACK signal is transmitted.

2.2 크로스 캐리어 스케줄링(Cross Carrier Scheduling)2.2 Cross Carrier Scheduling

In a carrier aggregation system, there are two types of a self-scheduling method and a cross carrier scheduling method in terms of scheduling for a carrier (or carrier) or a serving cell. Cross carrier scheduling may be referred to as Cross Component Carrier Scheduling or Cross Cell Scheduling.

Self-scheduling is transmitted through a DL CC in which a PDCCH (DL Grant) and a PDSCH are transmitted in the same DL CC, or a PUSCH transmitted according to a PDCCH (UL Grant) transmitted in a DL CC is linked to a DL CC in which a UL Grant has been received. It means to be.

In cross-carrier scheduling, a DL CC in which a PDCCH (DL Grant) and a PDSCH are transmitted to different DL CCs, or a UL CC in which a PUSCH transmitted according to a PDCCH (UL Grant) transmitted in a DL CC is linked to a DL CC having received an UL grant This means that it is transmitted through other UL CC.

Whether to perform cross-carrier scheduling may be activated or deactivated UE-specifically and may be known for each UE semi-statically through higher layer signaling (eg, RRC signaling).

When cross-carrier scheduling is activated, a carrier indicator field (CIF: Carrier Indicator Field) indicating a PDSCH / PUSCH indicated by the corresponding PDCCH is transmitted to the PDCCH. For example, the PDCCH may allocate PDSCH resource or PUSCH resource to one of a plurality of component carriers using CIF. That is, when the PDCCH on the DL CC allocates PDSCH or PUSCH resources to one of the multi-aggregated DL / UL CC, CIF is set. In this case, the DCI format of LTE Release-8 may be extended according to CIF. In this case, the set CIF may be fixed as a 3 bit field or the position of the set CIF may be fixed regardless of the DCI format size. In addition, the PDCCH structure (same coding and resource mapping based on the same CCE) of LTE Release-8 may be reused.

On the other hand, if the PDCCH on the DL CC allocates PDSCH resources on the same DL CC or PUSCH resources on a single linked UL CC, CIF is not configured. In this case, the same PDCCH structure (same coding and resource mapping based on the same CCE) and DCI format as in LTE Release-8 may be used.

When cross carrier scheduling is possible, the UE needs to monitor the PDCCHs for the plurality of DCIs in the control region of the monitoring CC according to the transmission mode and / or bandwidth for each CC. Therefore, it is necessary to configure the search space and PDCCH monitoring that can support this.

In the carrier aggregation system, the terminal DL CC set represents a set of DL CCs scheduled for the terminal to receive a PDSCH, and the terminal UL CC set represents a set of UL CCs scheduled for the terminal to transmit a PUSCH. In addition, the PDCCH monitoring set represents a set of at least one DL CC that performs PDCCH monitoring. The PDCCH monitoring set may be the same as the terminal DL CC set or may be a subset of the terminal DL CC set. The PDCCH monitoring set may include at least one of DL CCs in the terminal DL CC set. Alternatively, the PDCCH monitoring set may be defined separately regardless of the UE DL CC set. The DL CC included in the PDCCH monitoring set may be configured to always enable self-scheduling for the linked UL CC. The UE DL CC set, the UE UL CC set, and the PDCCH monitoring set may be configured UE-specifically, UE group-specifically, or cell-specifically.

When cross-carrier scheduling is deactivated, it means that the PDCCH monitoring set is always the same as the UE DL CC set. In this case, an indication such as separate signaling for the PDCCH monitoring set is not necessary. However, when cross-carrier scheduling is activated, it is preferable that a PDCCH monitoring set is defined in the terminal DL CC set. That is, in order to schedule PDSCH or PUSCH for the UE, the base station transmits the PDCCH through only the PDCCH monitoring set.

7 illustrates a subframe structure of an LTE-A system according to cross carrier scheduling used in embodiments of the present invention.

Referring to FIG. 7, three DL component carriers (DL CCs) are combined in a DL subframe for an LTE-A terminal, and DL CC 'A' represents a case in which a PDCCH monitoring DL CC is configured. If CIF is not used, each DL CC may transmit a PDCCH for scheduling its PDSCH without CIF. On the other hand, when the CIF is used through higher layer signaling, only one DL CC 'A' may transmit a PDCCH for scheduling its PDSCH or PDSCH of another CC using the CIF. At this time, DL CCs 'B' and 'C' that are not configured as PDCCH monitoring DL CCs do not transmit the PDCCH.

8 is a diagram illustrating an example of a configuration of a serving cell according to cross carrier scheduling used in embodiments of the present invention.

In a radio access system supporting carrier combining (CA), a base station and / or terminals may be composed of one or more serving cells. In FIG. 8, the base station can support a total of four serving cells, such as A cell, B cell, C cell, and D cell, and terminal A is composed of A cell, B cell, and C cell, and terminal B is B cell, C cell, and the like. It is assumed that the D cell and the terminal C is configured as a B cell. In this case, at least one of the cells configured in each terminal may be configured as a P cell. In this case, the PCell is always in an activated state, and the SCell may be activated or deactivated by the base station and / or the terminal.

The cell configured in FIG. 8 is a cell capable of adding a cell to a CA based on a measurement report message from a terminal among cells of a base station, and may be configured for each terminal. The configured cell reserves the resources for the ACK / NACK message transmission for the PDSCH signal transmission in advance. An activated cell is a cell configured to transmit a real PDSCH signal and / or a PUSCH signal among configured cells, and performs CSI reporting and SRS (Sounding Reference Signal) transmission. A de-activated cell is a cell configured not to transmit or receive a PDSCH / PUSCH signal by a command or timer operation of a base station, and also stops CSI reporting and SRS transmission.

2.3 CA 환경 기반의 CoMP 동작2.3 CoMP operation based on CA environment

Hereinafter, a cooperative multi-point (CoMP) transmission operation that can be applied to embodiments of the present invention will be described.

In the LTE-A system, CoMP transmission may be implemented using a carrier aggregation (CA) function in LTE. 9 is a conceptual diagram of a CoMP system operating based on a CA environment.

In FIG. 9, it is assumed that a carrier operating as a PCell and a carrier operating as an SCell may use the same frequency band as the frequency axis, and are allocated to two geographically separated eNBs. In this case, the serving eNB of the UE1 may be allocated to the Pcell, and the neighboring cell which gives a lot of interference may be allocated to the Scell. That is, the base station of the P cell and the base station of the S cell may perform various DL / UL CoMP operations such as joint transmission (JT), CS / CB, and dynamic cell selection with respect to one UE.

9 shows an example of combining cells managed by two eNBs for one UE (e.g. UE1) as a Pcell and an Scell, respectively. However, as another example, three or more cells may be combined. For example, some of the three or more cells may be configured to perform a CoMP operation on one terminal in the same frequency band, and other cells to perform a simple CA operation in another frequency band. At this time, the Pcell does not necessarily participate in CoMP operation.

2.4 참조신호(RS: Reference Signal)2.4 Reference Signal

Hereinafter, reference signals that can be used in embodiments of the present invention will be described.

10 shows an allocation structure of a CRS when a system supports four antennas. In 3GPP LTE / LTE-A system, CRS is used for decoding and channel state measurement. Accordingly, the CRS is transmitted over the entire downlink bandwidth in all downlink subframes in a cell supporting PDSCH transmission, and is transmitted in all antenna ports configured in the eNB.

Specifically, the CRS sequence is mapped to complex-valued modulation symbols used as reference symbols for antenna port p in slot n _s .

The UE can measure the CSI using the CRS, and can decode the downlink data signal received through the PDSCH in a subframe including the CRS using the CRS. That is, the eNB transmits the CRS at a predetermined position in each RB in all RBs, and the UE detects the PDSCH after performing channel estimation based on the CRS. For example, the UE measures the signal received at the CRS RE. The UE may detect the PDSCH signal from the PD to which the PDSCH is mapped by using a ratio of the reception energy for each CRS RE to the reception energy for each RE to which the PDSCH is mapped.

As such, when the PDSCH signal is transmitted based on the CRS, the eNB needs to transmit the CRS for all RBs, which causes unnecessary RS overhead. In order to solve this problem, the 3GPP LTE-A system further defines a UE-specific RS (hereinafter, UE-RS) and a channel state information reference signal (CSI-RS) in addition to the CRS. UE-RS is used for demodulation and CSI-RS is used to derive channel state information.

Since UE-RS and CRS are used for demodulation, they can be referred to as demodulation RS in terms of use. That is, the UE-RS may be regarded as a kind of DM-RS (DeModulation Reference Signal). In addition, since the CSI-RS and the CRS are used for channel measurement or channel estimation, the CSI-RS and CRS may be referred to as RS for channel state measurement in terms of use.

FIG. 11 is a diagram illustrating an example of subframes in which CSI-RSs that can be used in embodiments of the present invention are allocated according to the number of antenna ports.

The CSI-RS is a downlink reference signal introduced in the 3GPP LTE-A system not for demodulation purposes but for measuring a state of a wireless channel. The 3GPP LTE-A system defines a plurality of CSI-RS settings for CSI-RS transmission. In subframes in which CSI-RS transmission is configured, the CSI-RS sequence is mapped according to complex modulation symbols used as reference symbols on antenna port p.

FIG. 11 (a) shows 20 CSI-RS configurations 0 to 19 available for CSI-RS transmission by two CSI-RS ports among CSI-RS configurations, and FIG. 11 (b) shows CSI-RS configurations. Of the configurations, 10 CSI-RS configurations available through four CSI-RS ports 0 through 9 are shown, and FIG. 11 (c) shows 5 available by eight CSI-RS ports among the CSI-RS configurations. Branch CSI-RS configuration 0-4 are shown.

Here, the CSI-RS port means an antenna port configured for CSI-RS transmission. Since the CSI-RS configuration varies depending on the number of CSI-RS ports, even if the CSI-RS configuration numbers are the same, different CSI-RS configurations are obtained when the number of antenna ports configured for CSI-RS transmission is different.

On the other hand, unlike the CRS configured to be transmitted every subframe, the CSI-RS is configured to be transmitted every predetermined transmission period corresponding to a plurality of subframes. Therefore, the CSI-RS configuration depends not only on the positions of REs occupied by the CSI-RS in a resource block pair but also on the subframe in which the CSI-RS is configured.

In addition, even if the CSI-RS configuration numbers are the same, if the subframes for CSI-RS transmission are different, the CSI-RS configuration may be regarded as different. For example, if the CSI-RS transmission period (T _CSI-RS ) is different or the start subframe (Δ _CSI-RS ) configured for CSI-RS transmission in one radio frame is different, the CSI-RS configuration may be different.

Hereinafter, the CSI-RS configuration depends on (1) the CSI-RS configuration to which the CSI-RS configuration number is assigned, and (2) the CSI-RS configuration number, the number of CSI-RS ports, and / or subframes in which the CSI-RS is configured. In order to distinguish between them, the configuration of the latter 2 is called a CSI-RS resource configuration. The setting of the former 1 is also referred to as CSI-RS configuration or CSI-RS pattern.

When eNB informs UE of CSI-RS resource configuration, the number of antenna ports, CSI-RS pattern, CSI-RS subframe configuration I _CSI-RS , CSI used for transmission of _CSI-RSs UE assumption on reference PDSCH transmitted power for feedback (CSI) can be informed about P _c , zero power CSI-RS configuration list, zero power CSI-RS subframe configuration, etc. .

CSI-RS Subframe Configuration Index I _CSI-RS is information for specifying the subframe configuration period T _CSI-RS and subframe offset Δ _CSI-RS for the presence of _CSI-RSs . Table 4 below illustrates CSI-RS subframe configuration index I _CSI-RS according to T _CSI-RS and Δ _CSI-RS .

Table 6

CSI-RS-SubframeConfig I _CSI-RS	CSI-RS periodicity T _CSI-RS (subframes)	CSI-RS subframe offset Δ _CSI-RS (subframes)
0-4	5	I _CSI-RS
5-14	10	I _CSI-RS -5
15-34	20	I _CSI-RS -15
35-74	40	I _CSI-RS -35
75-154	80	I _CSI-RS -75

At this time, subframes satisfying Equation 3 below are subframes including the CSI-RS.

Equation 3

UE set to a transmission mode defined after 3GPP LTE-A system (for example, transmission mode 9 or another newly defined transmission mode) performs channel measurement using CSI-RS and PDSCH using UE-RS Can be decoded.

2.5 Enhanced PDCCH (EPDCCH)2.5 Enhanced PDCCH (EPDCCH)

In a 3GPP LTE / LTE-A system, when defining a cross carrier scheduling (CCS) operation in a combined situation for a plurality of component carrier (CC) cells, one scheduled CC (CC) is defined. In other words, the scheduled CC may be preset to receive DL / UL scheduling only from another scheduling CC (ie, to receive a DL / UL grant PDCCH for the scheduled CC). In this case, the scheduling CC may basically perform DL / UL scheduling on itself. In other words, a search space (SS) for a PDCCH for scheduling a scheduled / scheduled CC in the CCS relationship may exist in a control channel region of all scheduling CCs.

Meanwhile, in an LTE system, FDD DL carriers or TDD DL subframes use the first n (n <= 4) OFDM symbols of each subframe to transmit PDCCH, PHICH, and PCFICH, which are physical channels for transmitting various control information. And use the remaining OFDM symbols for PDSCH transmission. In this case, the number of OFDM symbols used for transmission of control channels in each subframe may be delivered to the UE dynamically through a physical channel such as PCFICH or in a semi-static manner through RRC signaling.

Meanwhile, in the LTE / LTE-A system, the PDCCH, which is a physical channel for transmitting DL / UL scheduling and various control information, has a limitation such as being transmitted through limited OFDM symbols. Thus, the PDCCH is transmitted through an OFDM symbol separate from the PDSCH, such as a PDCCH. An extended PDCCH (ie E-PDCCH) may be introduced, which is more freely multiplexed by PDSCH and FDM / TDM scheme instead of the control channel. FIG. 12 is a diagram illustrating an example in which legacy PDCCH, PDSCH, and E-PDCCH used in an LTE / LTE-A system are multiplexed.

2.6 제한된 CSI 측정2.6 Limited CSI Measurement

In order to reduce the influence of interference between cells in a wireless network, cooperative operations may be performed between network entities. For example, during a particular subframe in which Cell A transmits data, cells other than Cell A transmit only common control information, but do not transmit data, thereby minimizing interference to users receiving data in Cell A. can do.

In this way, it is possible to reduce the influence of interference between cells by transmitting only a minimum of common control information from other cells except cells that transmit data at a specific moment through cooperation between cells in the network.

To this end, when two CSI measurement subframe sets CCSI, 0 and CCSI, 1 are configured in an upper layer, the UE may perform a resource-restricted measurement (RRM) operation. In this case, it is assumed that the CSI reference resources corresponding to the two measurement subframe sets belong to only one of the two subframe sets.

Table 7 below shows an example of a higher layer signal for setting a CSI subframe set.

TABLE 7

CQI-ReportConfig-r10 :: = SEQUENCE {cqi-ReportAperiodic-r10 CQI-ReportAperiodic-r10 OPTIONAL,-Need ON nomPDSCH-RS-EPRE-Offset INTEGER (-1..6), cqi-ReportPeriodic-r10 CQI-ReportPeriodic -r10 OPTIONAL,-Need ON pmi-RI-Report-r9 ENUMERATED {setup} OPTIONAL,-Cond PMIRIPCell csi-SubframePatternConfig-r10 CHOICE {release NULL, setup SEQUENCE {csi-MeasSubframeSet1-r10 MeasSubframePattern-r10, csi-MeasSubframeSet2 -r10 MeasSubframePattern-r10}} OPTIONAL-Need ON}

Table 7 shows an example of a CQI-Report Cofig message transmitted to set a CSI subframe set. At this time, the CQI report configuration message includes aperiodic CQI report (cqi-ReportAperiodic-r10) IE, nomPDSCH-RS-EPRE-Offset IE, periodic CQI report (cqi-ReportPeriodci-r10) IE, PMI-RI report (pmi-RI- Report-r9) IE and CSI subframe pattern configuration (csi-subframePatternConfig) IE may be included. In this case, the CSI subframe pattern configuration IE includes a CSI measurement subframe set 1 information (csi-MeasSubframeSet1) IE and a CSI measurement subframe set 2 information (csi-MeasSubframeSet2) IE indicating a measurement subframe pattern for each subframe set.

Herein, the CSI measurement subframe set 1 (csi-MeasSubframeSet1-r10) information element (IE) and the CSI measurement subframe set 2 (csi-MeasSubframeSet2-r10) IE are 40 bit bitmap information and belong to each subframe set. Represents information about a subframe. In addition, the aperiodic CQI report (CQI-ReportAperiodic-r10) IE is an IE for performing the setting for aperiodic CQI reporting to the terminal, the periodic CQI report (CQI-ReportPeriodic-r10) IE is set for the periodic CQI reporting IE is done.

nomPDSCH-RS-EPRE-Offset IE

Indicates a value. At this time, the actual value is

Value * 2 is set to [dB]. In addition, the PMI-RI Report IE indicates that PMI / IR reporting is configured or not. EUTRAN configures the PMI-RI Report IE only when the transmission mode is set to TM8, 9 or 10.

3. LTE-U 시스템3. LTE-U system

3.1 LTE-U 시스템 구성3.1 LTE-U system configuration

Hereinafter, methods for transmitting and receiving data in a carrier combining environment of a licensed band, an LTE-A band and an unlicensed band, will be described. In the embodiments of the present invention, the LTE-U system refers to an LTE system supporting CA conditions of the licensed band and the unlicensed band. The unlicensed band may be a Wi-Fi band or a Bluetooth (BT) band.

13 is a diagram illustrating an example of a CA environment supported by the LTE-U system.

Hereinafter, for convenience of description, assume a situation in which the UE is configured to perform wireless communication in each of a licensed band and an unlicensed band using two component carriers (CCs). Of course, even if three or more CCs are configured in the UE, the methods described below may be applied.

In embodiments of the present invention, a licensed CC (LCC: Licensed CC) is a major carrier (can be referred to as a primary CC (PCC or PCell)), an unlicensed carrier (Unlicensed CC: UCC) is a sub-carrier Assume a case of (Secondary CC: SCC or S cell). However, embodiments of the present invention may be extended to a situation in which a plurality of licensed bands and a plurality of unlicensed bands are used in a carrier combining method. In addition, the proposed schemes of the present invention can be extended to not only 3GPP LTE system but also other system.

FIG. 13 illustrates a case in which one base station supports both a licensed band and an unlicensed band. That is, the terminal can transmit and receive control information and data through a PCC, which is a licensed band, and can also transmit and receive control information and data through an SCC, which is an unlicensed band. However, the situation shown in FIG. 13 is one example, and embodiments of the present invention may be applied to a CA environment in which one terminal accesses a plurality of base stations.

For example, the terminal may configure a P-cell and a macro base station (M-eNB: Macro eNB) and a small cell (S-eNB: Small eNB) and an S cell. At this time, the macro base station and the small base station may be connected through a backhaul network.

In embodiments of the present invention, the unlicensed band may be operated in a contention based random access scheme. In this case, an eNB and / or a transmission point (TP) supporting an unlicensed band may first perform a carrier sensing (CS) process before data transmission and reception. The CS process is a process of determining whether the corresponding band is occupied by another entity.

For example, the base station eNB and / or TP of the SCell checks whether the current channel is busy or idle. If it is determined that the corresponding band is idle, the base station and / or the TP is a scheduling grant through the (E) PDCCH of the Pcell in the case of the cross carrier scheduling scheme or the PDCCH of the Scell in the case of the self scheduling scheme. Transmits to the terminal to allocate resources, and may attempt to transmit and receive data.

[[The CS process may be performed in the same or similar manner as the LBT process. The LBT process is a process in which a base station of a Pcell checks whether a current state of a Ucell (a cell operating in an unlicensed band) is busy or idle. For example, when there is a clear channel assessment (CCA) threshold set by a preset or higher layer signal, when an energy higher than the CCA threshold is detected in the U-cell, it is determined to be busy or otherwise idle. do. When the Ucell is determined to be idle, the base station of the Pcell transmits a scheduling grant (ie, DCI, etc.) through the (E) PDCCH of the Pcell or through the PDCCH of the Ucell to schedule resources for the Ucell. The data can be transmitted and received through the U cell. ]]

In this case, the base station and / or the TP may set a transmission opportunity (TxOP) section consisting of M consecutive subframes. Here, the base station may inform the UE of the M value and the use of the M subframes in advance through a higher layer signal, a physical control channel, or a physical data channel through a Pcell. A TxOP period consisting of M subframes may be called a reserved resource period (RRP).

3.2 TxOP 구간3.2 TxOP section

The base station may transmit and receive data with one terminal during the TxOP period, or may set a TxOP period composed of N consecutive subframes to each of the multiple terminals and transmit and receive data in a TDM or FDM manner. At this time, the base station may transmit and receive data through the P cell and the S cell of the unlicensed band during the TxOP period.

However, if the base station transmits data in accordance with the subframe boundary of the LTE-A system, which is a licensed band, a timing gap may exist between the idle determination time of the unlicensed band and the actual data transmission time. Can be. In particular, the SCell is an unlicensed band that cannot be used exclusively by the corresponding base station and the terminal, and must be used through competition based on CS, so that another system may attempt to transmit information during such a timing gap.

Accordingly, the base station may transmit a reservation signal to prevent another system from attempting to transmit information during the timing gap in the SCell. Here, the reservation signal means a kind of "dummy information" or "copy of a part of PDSCH" transmitted to reserve a corresponding resource region of the SCell as its own resource. The reservation signal may be transmitted during a timing gap (i.e. after the idle determination time of the SCell to before the actual transmission time).

3.3 TxOP 구간 설정 방법3.3 How to Set TxOP Section

14 is a diagram illustrating one method of setting a TxOP interval.

The base station may set the TxOP interval in a semi-static manner in advance through the Pcell. For example, the base station may transmit the number N of subframes constituting the TxOP interval and configuration information on the purpose of the corresponding TxOP interval to the terminal through an upper layer signal (eg, an RRC signal) (S1410).

However, depending on the system configuration, step S1410 may be performed dynamically. In this case, the base station may transmit the configuration information for the TxOP interval to the terminal through the PDCCH or E-PDCCH.

The SCell may check whether a current channel state is idle or busy by performing a carrier sensing process (S1420).

The Pcell and the Scell may be managed by different base stations or the same base station. However, when different base stations are managed, information on the channel state of the SCell may be transferred to the PCcell through the backhaul (S1430).

Thereafter, the UE may transmit and receive data through the Pcell and the Scell in the subframe set to the TxOP period. If the use of the corresponding TxOP is set to downlink data transmission in step S1410, the UE may receive DL data through the Scell in the TxOP period, and if the use of the TxOP is set to uplink data transmission, the terminal is S UL data may be transmitted through the cell (S1440).

4. 비면허대역에 대한 CSI 보고 방법4. CSI reporting method for unlicensed band

4.1 PAP 및 non-PAP 구성 방법4.1 How to Configure PAP and Non-PAP

By performing the LBT process (and / or the CS process), it is desirable to be prepared in case UCell does not occupy the channel for too long. That is, in the embodiments of the present invention, a section for unconditionally transmitting data without performing LBT in the U cell may be configured.

Alternatively, the base station of the Pcell may perform an LBT process, but may be configured to attempt an aggressive channel access by setting a relatively high CCA threshold during a specific period.

Alternatively, an exclusive channel access interval may be set through information exchange between intra operator inter cells, between operators and / or inter RAT (eg Radio Access Technology) (eg, WiFi). have.

These intervals may be defined as a Preoccupied Access Period (PAP). Also, non-PAP is defined as the section other than the relevant section. In this case, the (non-) PAP may be set cell-specifically or may be set UE-specifically.

In embodiments of the present invention, the (non-) PAP may be set by higher layer signaling (eg, RRC or MAC signal) or physical layer signaling (eg, PDCCH or E-PDCCH).

4.2 비면허 대역에서 제한적 CSI 측정 집합 설정 방법4.2 How to set up a limited set of CSI measurements in the unlicensed band

In the embodiments of the present invention, if PAP is defined as a section that does not perform the LBT process (or CS process), PAP is more vulnerable to interference by inter-operator U-cell or WiFi system than non-PAP. Can lose. That is, since CSI measurement results performed in non-PAP and PAP may be different, it is preferable to set a limited CSI measurement set for each section.

For example, non-PAP may be set to CSI subframe set 0 and PAP to CSI subframe set 1. In this case, periodic CSI reporting may be configured for each CSI subframe set.

Aperiodic CSI reporting triggering can be initiated regardless of the CSI subframe set. However, CSI reporting triggering may be defined to be set only in a TxOP period in PAP and non-PAP. This is because the interference such as the WiFi system is measured in the non-TxOP section in the non-PAP, and a larger amount of interference may be measured than the interference to be measured in the actual RRP section, thereby assigning a low MCS level. Therefore, in the embodiments of the present invention, the UE may consider that the aperiodic CSI report triggered in a section that is not a PAP or that is not a TxOP section in a non-PAP is invalid.

In the existing LTE / LTE-A system, periodic or aperiodic CSI reporting may be performed for all CSI subframe sets. However, in embodiments of the present invention, CSI reporting may be performed only for one of the CSI subframe sets according to the characteristics of the PAP or non-PAP interval.

4.2.1 주기적 CSI 보고 방법4.2.1 Periodic CSI Reporting Method

The probability that a data transmission will actually occur during PAP is much greater than the probability that a data transmission will occur during non-PAP. Therefore, the periodic CSI report transmitted by the terminal during PAP may be more meaningful than the CSI report transmitted during non-PAP.

However, when it is confirmed that the U-cell is busy by performing LBT during non-PAP, the impact due to interference such as WiFi may be less than that during the PAP. In this case, the base station can greatly bring about a link adaptation effect according to periodic CSI reporting in the non-PAP.

Accordingly, the base station of the Pcell may configure periodic CSI reporting only for one specific CSI subframe set among two CSI subframe sets 0 and 1 set to non-PAP or PAP in the U cell.

In case of the LTE / LTE-A system, when two CSI subframe sets are configured in the UE, the UE performs CSI reporting on the two CSI subframe sets. In the embodiment of the present invention, periodic CSI reporting may be performed only for subframe set 0 or 1 configured in the unlicensed band.

Referring to FIG. 15, a base station of a Pcell supporting a licensed band (that is, an LTE-A system band) may use a higher layer signal to configure a subframe set (SF) for an Scell (or Ucell) that supports an unlicensed band. set) configuration information may be transmitted to the terminal. At this time, the subframe set configuration information may be set to the CSI subframe set 0 and 1 for the non-PAP and PAP configured in the SCell (S1510).

When the Pcell and the Scell are configured in a cross carrier scheduling (CCS) scheme, the base station of the Pcell is a PDCCH or E-PDCCH including scheduling information on a TxOP interval in the PAP or non-PAP of the Scell. (Hereinafter, (E) PDCCH) can be transmitted. If the Pcell and the SCell are configured in a Self Carrier Scheduling (SCS) scheme, the (E) PDCCH may be transmitted through the SCell (S1520).

The SCell may transmit DL data to the UE through PDSCH based on the scheduling information transmitted through the (E) PDCCH. In this case, the terminal may receive DL data in a valid subframe (SF). In this case, the effective SF may mean an SF configured in the PAP or an SF corresponding to a TxOP section configured in the non-PAP (S1530).

The UE may measure CSI and / or interference for the effective SF. In this case, the UE may be configured to measure CSI and / or interference only for the CSI subframe set 0 or 1. For example, the UE may measure CSI in CSI subframe set 1 allocated in the PAP. Or, the UE can measure CSI or interference in CSI subframe set 0 corresponding to the TxOP interval in the non-PAP (S1540).

The UE may periodically report the CSI and / or interference measured through the PUCCH or the PUSCH to the Pcell base station or the Scell (S1550).

4.2.2 비주기적 CSI 보고 방법4.2.2 Aperiodic CSI Reporting Method

The limited CSI measurement set described above may be set to a Rel-12 CSI subframe set. For example, non-PAP may be set to Rel-12 CSI subframe set 0, and PAP may be set to Rel-12 CSI subframe set 1.

At this time, the aperiodic CSI trigger may indicate which CSI subframe set is triggered in which CSI subframe set among two limited CSI measurement sets. That is, the aperiodic CSI request field (ie, CSI trigger) included in the PDCCH may be configured to indicate a set of CSI subframes that are subject to aperiodic CSI reporting. For example, when the CSI request field is 2 bits, it indicates that aperiodic CSI reporting for CSI subframe set 0 is triggered when the CSI request field is set to '00', and when set to '01', CSI subframe set 1 It may indicate that aperiodic CSI reporting for is triggered. The setting value of the CSI request field may be changed depending on the system.

A terminal of an LTE system (ie, Rel-10) may measure CSI only for a set of CSI subframes configured therein. However, the UE of the LTE-A system (ie, Rel-12) may measure and report the CSI not only for the CSI subframe set configured therein but also for other CSI subframe sets. Accordingly, in embodiments of the present invention, the UE can measure CSI for both CSI subframe sets 1 and 0 configured for PAP and non-PAP, and can report CSI according to the CSI request field transmitted from the base station. have.

Referring to FIG. 16, a base station of a Pcell supporting a licensed band (that is, an LTE-A system band) may use a subframe set (SF) for an SCell (or Ucell) that supports an unlicensed band using a higher layer signal. set) configuration information may be transmitted to the terminal. At this time, the subframe set configuration information may be set to the CSI subframe set 0 and 1 for the non-PAP and PAP configured in the SCell (S1610).

When the Pcell and the Scell are configured in a Cross Carrier Scheduling (CCS) scheme, the base station of the Pcell may include (E) PDCCH including scheduling information on the TxOP interval in the PAP or non-PAP of the Scell. Can transmit If the Pcell and the SCell are configured in a Self Carrier Scheduling (SCS) scheme, the (E) PDCCH may be transmitted through the SCell. In this case, the base station may further include a CSI request field in the (E) PDCCH to trigger the aperiodic CSI report (S1620).

In this case, the CSI request field transmitted in step S1620 may indicate to report the CSI for the CSI SF set 1 for the PAP or the CSI SF set 0 for the non-PAP.

The SCell may transmit DL data to the UE through PDSCH based on the scheduling information transmitted through the PDCCH. In this case, the terminal may receive DL data in a valid subframe (SF). In this case, the effective SF may refer to SF configured in the PAP or SF corresponding to the TxOP section configured in the non-PAP (S1630).

The UE may measure CSI and / or interference for the effective SF. The UE may be configured to measure CSI and interference for the CSI subframe sets 0 and 1. For example, the UE may measure CSI and / or interference in the CSI subframe set 0 corresponding to the CSI for the CSI subframe set 1 allocated in the PAP and the TxOP interval in the non-PAP (S1640).

The UE may aperiodically report the CSI for the CSI subframe set indicated by the CSI request field in step S1620 of the measured CSI subframe sets 0 and 1 to the base station. At this time, the aperiodic CSI may be transmitted to the Pcell or Scell through the PUSCH (S1650).

4.2.3 간섭 측정4.2.3 Interference Measurement

The base station eNB may attempt data transmission unconditionally during the configured PAP, but may perform data transmission only when the channel is idle (ie, only during the configured TxOP period) during the non-PAP.

If the TxOP interval is not set among the non-PAP, unexpected interference may occur by the LTE base station between the WiFi system or the operator. Therefore, when performing interference measurement during non-PAP, the UE preferably takes time domain averaging for the amount of interference measured in the TxOP period. That is, in order to perform interference measurement, the UE preferably utilizes TxOP interval configuration information (see FIG. 14) as well as PAP configuration.

In an embodiment of the present invention, the terminal may be configured to perform interference measurement only in the PAP interval in order to reduce the complexity thereof. For example, if PAP is defined as CSI subframe set 1 and non-PAP is defined as CSI subframe set 0, the UE may perform interference measurement only on CSI subframe set 1.

It is assumed that further enhanced inter-cell interference coordination (FeICIC) or Network Assisted Interference Cancellation and Suppression (NAICS) is used. At this time, when the eNB informs the UE of information (eg, cell ID, port number, RS type, Tx power, SF usage, etc.) for severe interference (ie, aggressor cell), the information is defined to be valid only in the PAP. Can be. This is because data transmission is not deterministic in a cell with high interference in a non-PAP period.

Or, the information on the cell with a severe interference received by the terminal is guaranteed only in the PAP, and during the non-PAP, the UE may be configured to determine whether the cell with a severe interference actually transmits data through blind detection (BD). .

For example, in FIG. 15 and FIG. 16, when the UE measures CSI or only measures interference, the UE may measure interference only in the CSI subframe set defined during PAP.

4.2.4 차분 전력 제어(Differential Power Control)4.2.4 Differential Power Control

If PAP is defined as a section that does not perform the LBT process (or CS process), the interference may significantly affect the next cell or another system, WiFi, during the corresponding section. In consideration of this, power can be set differently according to whether PAP or non-PAP is used. For example, downlink power control related parameters (e.g., P_a, P_b, P_c, etc.) may be set differently for each CSI subframe set.

In addition, considering whether the interference environment and the transmission power are different depending on whether the PAP or non-PAP, a transmission mode (TM) or PDSCH CRS transmission can be set differently. For example, since the base station can transmit with reduced power during the PAP in the SCell, in order to increase the probability of success of PDSCH transmission, the CRS is transmitted only to UEs of DM-RS based TM (ie, TM 9 or higher), not CRS based TM. PDSCH can be configured (eg, MBMS subframe) and transmitted.

The above-described downlink power control related parameters may be transmitted to the terminal through higher layer signaling or physical layer signaling. 15 and 16, in step S1510 and step S1610 (or steps S1520 and S1620), the base station may transmit a downlink power adjustment related parameter to the terminal. The UE may receive DL data with reference to downlink power set differently according to PAP or noo-PAP in steps S1530 and S1630.

4.3 제한된 측정 집합이 설정되지 않은 경우의 CSI 보고 방법4.3 CSI reporting method when no limited set of measurements is set

In the embodiments described below, a CSI reporting method is described when a limited CSI measurement set is not set according to whether PAP or non-PAP.

4.3.1 주기적 CSI 보고 방법4.3.1 Periodic CSI Reporting Method

To this end, the base station may set the valid CSI measurement interval only during the PAP, or only the TxOP interval of the non-PAP as a valid CSI measurement interval. If only the TxOP section of the non-PAP is set as a valid CSI measurement section, the periodic CSI report may be limited to the TxOP section of the non-PAP. For example, in FIG. 15, the UE may periodically report by measuring the CSI for the Cx subframe set for the TxOP interval and the PAP in the non-PAP interval.

4.3.2 비주기적 CSI 보고 방법4.3.2 Aperiodic CSI Reporting Method

The UE may be configured to assume that only aperiodic CSI triggers within a valid CSI measurement interval are valid, and to ignore aperiodic CSI triggers of the remaining intervals. For example, in FIG. 16, the UE may perform CSI reporting to the base station only for the aperiodic CSI trigger in the PAP and / or the aperiodic CSI trigger transmitted in the TxOP period in the non-PAP.

Alternatively, the terminal may be configured to perform CSI reporting on a section that is not a valid CSI measurement section through an aperiodic CSI request field. For example, if the aperiodic CSI request field value is set to '01', then CSI reporting for a valid measurement interval is triggered; if the aperiodic CSI request field is set to '10', CSI for an invalid measurement interval It may indicate that the report has been triggered. For example, referring to FIG. 16, if the CSI request field is set to '01' in step S1620, the UE may report only the CSI for the TxOP interval in the PAP and / or non-PAP to the base station. If the CSI request field is set to '10', the terminal may report to the base station about the CSI measured in the section other than the TxOP section in the non-PAP.

4.3.3 RRM 측정 방법-14.3.3 RRM Measurement Method-1

In the LTE-A system (ie, Rel-12 system), SCell is defined not to perform limited Radio Resource Management (RRM) measurement.

If the PAP is defined as a section that does not perform the LBT process, the RRM measurement process may be defined only within a TxOP section for a non-PAP that is not relatively exposed to interference such as WiFi.

Alternatively, if the PAP is defined as an exclusive channel access interval established through inter cell information exchange, the RRM measurement process may be performed only within the PAP. That is, the UCell may be configured to perform a characteristically limited RRM measurement process.

4.4 셀간 조정 방법4.4 How to adjust between cells

For the PAP section, by using resources as orthogonal as possible through cell or inter-operator information exchange, interference can be greatly mitigated and resources can be efficiently utilized.

However, in the S cell, PAP and non-PAP may be set semi-statically rather than dynamically configured. Accordingly, PAP configuration information may be exchanged and shared with each other through a backhaul network between cells or between providers even with a certain amount of signaling latency.

4.4.1 사업자간 PAP 설정 정보 공유 방법-14.4.1 How to Share PAP Configuration Information Between Operators-1

Hereinafter, a method of setting sharing of PAP configuration information between an operator base station (intra-operator eNB) will be described.

By sharing the PAP configuration information, all base stations operated by different operators can be configured to perform the same operation during the PAP. For example, all eNBs may not perform the LBT process in the configured PAP. In this case, the shared PAP configuration information may be a start point of the PAP and a PAP length (or end point of the PAP).

If all eNBs attempt to transmit in PAP, performance degradation of UEs located at the cell edge may be severe. Accordingly, the base stations can mitigate the interference by dividing the PAP by the TDM scheme. For example, two adjacent eNBs may not interfere with each other by dividing PAP into two in a TDM manner.

More specifically, assume that PAP is set for 10 ms and non-PAP is set for the next 20 ms. In this case, adjacent eNB1 and eNB2 may divide the PAP section of 10 ms into two parts. For example, eNB1 may transmit DL data and eNB2 may not attempt transmission or may be set to non-PAP for the first 5 ms. For the remaining 5 ms, eNB2 transmits DL data, and eNB1 may not attempt to transmit or may be set to non-PAP.

Alternatively, the eNB1 and the eNB2 may not use the PAP evenly, but may use the PAP differentially according to the traffic load state. That is, an eNB with a larger traffic load may be configured to be assigned more PAP intervals.

4.4.2 사업자간 PAP 설정 정보 공유 방법-24.4.2 How to Share PAP Setting Information Between Businesses-2

Hereinafter, another method of configuring sharing of PAP configuration information between an operator base station (intra-operator eNB) will be described.

If a specific base station transmits DL data unconditionally without considering another base station of the PAP interval, the specific base station may receive a large interference from the eNB of the other operator periodically in the PAP. Therefore, it is desirable to reduce interference through coordination between operators.

That is, although the PAP is set to the TDM scheme, the eNBs of the operator B may be set to non-PAP for the PAP set by the operator A's base station. Alternatively, for the PAP set by the operator B, the eNBs of the operator A may be set to non-PAP. At this time, the operation of the PAP set by each provider may be defined as in Section 4.4.1.

PAP intervals can be set differently than described in Sections 4.4.1 and 4.4.2. For example, eNB1 of operator A may implicitly notify eNB2 of operator B that the interval is set to PAP by transmitting a preamble at the start and / or end of the PAP interval (or non-PAP interval). .

4.5 RRM 측정 방법-24.5 RRM Measurement Method-2

When the UE performs the RRM measurement for the neighbor cell, the RRM measurement process may vary depending on whether the neighbor cell is currently PAP or non-PAP. In this case, information on whether the neighbor cell is PAP or non-PAP (ie PAP configuration information) may be obtained through the inter-cell coordination method proposed in Section 4.4.

If the neighbor cell is non-PAP, DL data is not always transmitted in the cell. Therefore, the UE additionally needs information on whether the neighbor cell is a TxOP interval, and the UE may perform RRM measurement only in the TxOP interval.

However, since the TxOP interval is set dynamically, it may be difficult to perform intercell adjustment through the backhaul. Accordingly, the base station transmits PAP configuration information of the neighbor cell to each UE, and each UE can perform the RRM measurement process for the neighboring cell only during the PAP. That is, the UE is configured to perform the RRM measurement process only when the neighbor cell corresponds to the PAP, and not perform the RRM measurement process in the case of non-PAP.

5. 구현 장치5. Implement device

A UE may operate as a transmitting end in uplink and a receiving end in downlink. In addition, an e-Node B (eNB) may operate as a receiving end in uplink and a transmitting end in downlink.

That is, the terminal and the base station may include

transmitters

1740 and 1750 and

receivers

1750 and 1770 to control the transmission and reception of information, data and / or messages, respectively. Or

antennas

1700 and 1710 for transmitting and receiving messages.

In addition, the terminal and the base station may each include a processor (1720, 1730) for performing the above-described embodiments of the present invention and a memory (1780, 1790) that can temporarily or continuously store the processing of the processor, respectively. Can be.

Embodiments of the present invention can be performed using the components and functions of the above-described terminal and base station apparatus. For example, the base station may configure PAP and non-PAP, and configure the CSI subframe set, respectively. The base station may transmit configuration information on the set CSI subframe set to the terminal through a higher layer signal. The UE may measure the CSI for the CSI subframe set configured in the PAP or non-PAP, and report the CSI periodically or aperiodically to the base station. In this case, the periodic CSI may be defined only for one of two CSI subframe sets configured in the terminal. For details, see Sections 1 to 4.

The transmitter and the receiver included in the terminal and the base station include a packet modulation and demodulation function, a high speed packet channel coding function, an orthogonal frequency division multiple access (OFDMA) packet scheduling, and a time division duplex (TDD) for data transmission. Packet scheduling and / or channel multiplexing may be performed. In addition, the terminal and the base station of FIG. 17 may further include a low power radio frequency (RF) / intermediate frequency (IF) unit.

Meanwhile, in the present invention, the terminal is a personal digital assistant (PDA), a cellular phone, a personal communication service (PCS) phone, a GSM (Global System for Mobile) phone, a WCDMA (Wideband CDMA) phone, an MBS. A Mobile Broadband System phone, a hand-held PC, a notebook PC, a smart phone, or a Multi Mode-Multi Band (MM-MB) terminal may be used.

Here, a smart phone is a terminal that combines the advantages of a mobile communication terminal and a personal portable terminal, and may mean a terminal incorporating data communication functions such as schedule management, fax transmission and reception, which are functions of a personal mobile terminal, in a mobile communication terminal. have. In addition, a multimode multiband terminal can be equipped with a multi-modem chip to operate in both portable Internet systems and other mobile communication systems (e.g., code division multiple access (CDMA) 2000 systems, wideband CDMA (WCDMA) systems, etc.). Speak the terminal.

Embodiments of the invention may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

In the case of a hardware implementation, the method according to embodiments of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs). Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. For example, software code may be stored in the

memory units

1780 and 1790 and driven by the

processors

1720 and 1730. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The invention can be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. In addition, the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship or may be incorporated as new claims by post-application correction.

Embodiments of the present invention can be applied to various wireless access systems. Examples of various radio access systems include 3rd Generation Partnership Project (3GPP), 3GPP2 and / or IEEE 802.xx (Institute of Electrical and Electronic Engineers 802) systems. Embodiments of the present invention can be applied not only to the various radio access systems, but also to all technical fields to which the various radio access systems are applied.

Claims

In a method for a terminal to report channel state information (CSI) in a wireless access system supporting an unlicensed band,

Receiving an upper layer signal including CSI subframe aggregation configuration information from a base station through a primary cell (P cell);

Measuring a CSI for a secondary cell (S cell) in a PAP or a non-PAP based on the CSI subframe set configuration information; And

Transmitting the CSI report including the measured CSI to the base station,

The non-PAP is set to a first CSI subframe set, the PAP is set to a second CSI subframe set,

The terminal receives the first CSI subframe set and the second CSI subframe set through the CSI subframe set configuration information.

The SCell is configured in the unlicensed band.
The method of claim 1,

The PAP is a period in which data is transmitted and received regardless of whether the SCell is in an idle state.

The non-PAP is a CSI reporting method is a period in which data is transmitted and received only in the transmission opportunity period (TxOP) when the SCell is idle.
The method of claim 2,

If the CSI report is a periodic CSI report transmitted periodically,

The terminal measures the CSI for the second CSI subframe set and transmits the CSI report to the base station, CSI reporting method.
The method of claim 2,

If the CSI report is a periodic CSI report transmitted periodically,

The terminal measures the CSI in the TxOP in the first CSI subframe set and transmits the CSI report to the base station, CSI reporting method.
The method of claim 2,

If the CSI report is an aperiodic CSI report requested by the base station,

Receiving a physical downlink control channel including an aperiodic CSI request field from the Pcell,

Wherein the aperiodic CSI request field is configured to request CSI reporting for the first CSI subframe set or the second CSI subframe set.
The method of claim 2,

The terminal is configured to perform interferometry for the neighbor cell only in the second subframe set, CSI reporting method.
The method of claim 2,

Receiving downlink data from the SCell further;

The power control parameter used when transmitting the downlink data is set differently for each of the first subframe set and the second subframe set.
A terminal for reporting channel state information (CSI) in a wireless access system supporting an unlicensed band,

transmitter;

receiving set; And

A processor operatively coupled with the transmitter and the receiver, the processor configured to report the CSI;

The processor is:

Receiving an upper layer signal including CSI subframe aggregation configuration information from a base station through a primary cell (P cell) by controlling the receiver;

Measure a CSI for a secondary cell (S cell) in a PAP or a non-PAP based on the CSI subframe set configuration information; And

And control the transmitter to transmit the CSI report including the measured CSI to the base station,

The non-PAP is set to a first CSI subframe set, the PAP is set to a second CSI subframe set,

The terminal receives the first CSI subframe set and the second CSI subframe set through the CSI subframe set configuration information.

The SCell is configured in the unlicensed band.
The method of claim 8,

The PAP is a period in which data is transmitted and received regardless of whether the SCell is in an idle state.

The non-PAP is a terminal in which data is transmitted and received only in a transmission opportunity section (TxOP) in which the SCell is in an idle state.
The method of claim 9,

If the CSI report is a periodic CSI report transmitted periodically,

The terminal measures only the CSI for the second CSI subframe set, and transmits the CSI report to the base station.
The method of claim 9,

If the CSI report is a periodic CSI report transmitted periodically,

The terminal measures the CSI in the TxOP in the first set of CSI subframes, and transmits the CSI report to the base station.
The method of claim 9,

If the CSI report is aperiodic CSI report by the request of the base station,

The processor is configured to control the receiver to receive a physical downlink control channel including an aperiodic CSI request field from the Pcell,

The aperiodic CSI request field is configured to request CSI reporting for the first CSI subframe set or the second CSI subframe set.
The method of claim 9,

The terminal is configured to perform interferometry for the neighbor cell only in the second subframe set.
The method of claim 9,

Receiving downlink data from the SCell further;

The power control parameter used when transmitting the downlink data is set differently for each of the first subframe set and the second subframe set.